Electric Power

New Electric Driveline Options

new electric driveline options

The basic electric driveline layout will often mimic the diesel driveline, simply replacing one component with another, but there are some new electric driveline options.Because the power can be transmitted as electrical energy and not just as mechanical energy, different options become available.

One option which was evident at the Brisbane Truck Show last year was the e-Axle. This uses an axle mounted component to handle several of the driveline tasks. The power comes from the battery, though the inverter to an axle mounted assembly which is electric motor, transmission and differential all in one piece.

This substantially reduces driveline complexity and reduces packaging requirements. The complete unit on the axe does not take up much more space than the current differentials in a traditional driveline.

A more radical approach again is the introduction of the e-Hub. In this case, the power from the battery will go through one inverter for each drive wheel. That AC output goes to a large assembly at the wheel hub, which includes an electric motor, a transmission and wheel hub.

new electric driveline options

Again, this design has a benefit in packaging. The only components attached to the chassis are batteries and inverters, the rest are mounted at the wheel itself. At this point the driveline looks completely different to the traditional layout.

As a way of comparing the two drivelines, Dana look at the figures around an electric drive system, the Dana TM4 SUMO LD HV1200 electric motor up against a Cummins 6.7-litre truck engine. The diesel puts out 1152Nm (850 ft lb) of torque while the TM4 produces 1200Nm (850 ft lb). Power from the Cummins is 375hp (276kW) while the TM4 produces 272hp (200kW). The mass of that Cummins is 480 kg, while the inverter weighs 12kg and the motor 87kg, a total of 99kg. This is a substantial difference of 381kg.

The other components to compare are fuel tanks to batteries. This is more difficult to ascertain. We know how heavy a diesel tank to get the truck 500km will be and a matching battery may well be able to keep driveline mass in the same ballpark. However, battery technology is progressing very fast, and we know that a battery to get an electric truck 500km will be lighter next year than it is this year.

While the diesel flows from the tanks to the internal combustion engine, the battery array on a truck needs a battery management system to control charge. Fuel lines are replaced by the bright orange cabling we see prominently on electric trucks.

The high voltage cables have to meet ISO6469 (hence the orange colour), so truck manufacturers have to ensure the correct shielding, insulation and keep outside the maximum bending radius rules when routing the supply. These requirement do add substantial cost to the electric truck’s power system. Layouts using e-Hubs and e-Axles can reduce that cost, as much of the cabling is already enclosed.

new electric driveline options

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